The Mais Médicos (More Doctors) Program has led to an increase in the number of doctors and medical treatment in primary health care services across Brazil. This article presents the results of a case-control study of groups of municipalities based on secondary data sources. It aims to explore and discuss a set of indicators of primary health care service delivery. An improvement in performance against structural indicators was observed in municipalities where the program was implemented. With respect to the outcome indicators, a slight improvement in service delivery was observed in municipalities where the program was implemented. However, no difference was observed in impacts between the case and control municipalities. These results may have been influenced by the fact that the program has only been underway for a limited time, by underreporting of doctors by the National Health Facilities Register (CNES, acronym in Portuguese), and the predominantly substitutive nature of the allocation of medical professionals under the program in the selected municipalities.